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Chapter 3. Communications Operations of BHT-6000
EOT
ACK
3 seconds
3 seconds
ENQ (1)
ENQ (2)
EOT
ENQ (9)
3 seconds
■ Abnormal termination of phase 2 (Abort of phase 2)
If the sending station receives no ACK from the receiving station after sending an
ENQ nine times in succession, it sends an EOT to the receiving station after 3
seconds from the 9th ENQ to terminate this transmission sequence abnormally.
Sending
station
Receiving
station
Phase 3: Release of Data Link
■ Normal phase 3
The sending station transmits an EOT to the receiving station. Upon receipt of an
ACK from the receiving station, the sending station terminates the message trans-
mission normally and releases the data link.
Sending
station
Receiving
station
Normal
termination
Abnormal
termination